I. Field of the Invention
The present invention pertains generally to the field of communications, and more particularly to the broadcast of short message service for wireless communication systems.
II. Background
In a wireless communication system, the broadcast short message service (SMS) allows the transmission of short messages from a subscription service to a mobile unit. Generally, broadcast SMS messages are messages associated with services subscribed to by a user. Broadcast SMS can comprise entry features, administration features, or information messages. For example, a subscriber may subscribe to a stock quotes service wherein the subscriber will receive stock quotes on a wireless device or a mobile unit, such as a personal data assistant (PDA), laptop computer, a cellular telephone or a PCS telephone, from a subscription service utilizing the wireless communication system.
Various over-the-air interfaces have been developed for wireless communication systems including, e.g., frequency division multiple access (FDMA), time division multiple access (TDMA), and code division multiple access (CDMA). In connection therewith, various domestic and international standards have been established including, e.g., Advanced Mobile Phone Service (AMPS), Global System for Mobile Communications (GSM), and Interim Standard 95 (IS-95).
An exemplary wireless telephony communication system is a code division multiple access (CDMA) system. The IS-95 standard and its derivatives, IS-95A, IS-95B, IS-2000, proposed high-data-rate CDMA standards exclusively for data, etc. (referred to collectively herein as IS-95), are promulgated by the Telecommunication Industry Association (TIA) and other well known standards bodies to specify the use of a CDMA over-the-air interface for cellular or PCS telephony communication systems. Exemplary wireless communication systems configured substantially in accordance with the use of the IS-95 standard are described in U.S. Pat. Nos. 5,103,459 and 4,901,307, which are assigned to the assignee of the present invention and fully incorporated herein by reference.
A problem arises when a broadcast SMS message is transmitted over the wireless communication system. The mobile units that are subscribers to the subscription service must acquire the broadcast SMS message in a timely manner, but in order to do so, the mobile units must be awakened from an idle state. The process of xe2x80x9cwaking upxe2x80x9d from the idle state, demodulating the SMS message broadcast from a base station, and then returning to the idle state involves a power drain on each mobile unit""s battery that can measurably diminish the power level of the mobile unit""s battery. The length of time in which the mobile unit spends awake is approximately proportional to the power consumption of the mobile unit.
Hence, there is a present need to minimize the total battery drain of the mobile unit while allowing the mobile unit to detect and process broadcast SMS messages in a timely manner.
The present invention is directed to a method for transmitting and receiving broadcast SMS messages over a broadcast channel in a wireless communication system, comprising the steps of: generating a parameter message to be broadcast from a base station to a mobile unit, wherein the parameter message contains a set of transmission parameters for the broadcast channel; processing the parameter message at the mobile unit; and setting a periodic wake up schedule for the mobile unit in accordance with the set of transmission parameters, wherein the mobile unit wakes up periodically in order to detect a broadcast SMS message in one or more assigned broadcast channel frames. The period for each category of broadcast SMS messages may be different and the period may apply to a single broadcast channel. Messages arriving aperiodically can be queued and transmitted in pre-scheduled broadcast channel frames. Messages with inter-arrival interval greater than the specified transmission period are simply repeated.